In each city, the first place to look for a tinker is in proximity to the provisioner & cobbler (examples: Luna, Umbra). If the tinker isn't with them, then the Tinker has his own shop, and probably has two Tinkers in the building instead of one.
I'm not sure if the Vagabonds that are in some random Gypsy camp spawns in Ilshenar count as Tinkers (the way Iron Workers count as smiths), though their sales inventory would seem to indicate it might be true (or if not, something we can ask the devs about adding).
With the colored metal jewelry BODs, consider using them bribed up for mid-range rewards (up to 800 points) turned in directly (not banking) - especially the POF Kegs, ore maps, and the smelting talismans. For some of the other items, you might want some of the 25-charge master craftsman talismans as well.